This invention relates generally to hand trucks and dollies, and particularly to an upright two-wheeled hand truck for use in transporting office file cabinets.
Conventional hand trucks of many designs are known to the art, the most common being the upright, two-wheeled hand truck such as disclosed in U.S. Pat No. 4,420,166 to Law. Such hand trucks can take on any one of several configurations, such as those shown in U.S. Pat Nos. 3,927,898 to Weyrauch and 3,997,182 to Mortenson.
The general drawbacks involved in using an upright, two-wheeled hand truck are the difficulty in lifting or tilting the truck when raising a heavy load into a balanced position on two wheels, providing a suitably stable support for the load when on the truck, and restraining that load when the truck is being moved and the operator cannot hold the load onto the truck manually.
To overcome these problems, many specialized hand trucks have been developed to handle particular types or shapes of cargo. Features such as pivoting toe plate extensions for additional leverage and balance have been added, as well as modifications or attachments for using the hand truck in certain environments such as on stairways or to make those hand trucks convertible for use as four-wheeled carts or office trolleys. Examples of such features are shown in U.S. Pat Nos. 3,079,168 to Monroe; 3,997,182 to Mortenson; and 3,193,123 to Wouden.
In order to secure the load to the hand truck, various cables, ties, and elastic cords have been used. Such securing means are also common to luggage carts, bicycle racks, and trailers. In the case of large furniture or appliances, webbed straps with adjustable buckles are frequently used by movers, both to secure the load to the hand truck and also within the van or truck. Representative examples of such cords and webbing straps are shown in U.S. Pat. No. 4,175,769 to Kazmark and 4,591,183 to Gordon.
The use of a telescoping or adjustable handle having a variable length has also proven desirable in some applications, representative examples of such hand trucks being shown in U.S. Pat. Nos. 4,286,796 to Esposito and 4,570,953 to McPeak, and similar adjustable handles can also useful in collapsible luggage carts such as those shown in U.S. Pat. Nos. 4,040,642 to David or 3,827,707 to Bierman.
One particular area which has received much attention is the handling of barrels, drums, and similar cylindrical containers. Hand trucks having curved back frames to permit the drums to rest further back on the toe plate to increase leverage are well known, as are various hand trucks and fork lifts which carry the drums in a reclining or horizontal position.
Another development that has proven useful with handling drums is to place a clasp or claw on the frame of the hand truck which clips over and engages the upwardly projecting circumferential top rim of the drum, and prevents the drum from tipping forward when the hand truck is pivoted onto its wheels. Several various designs of these clasps or clamps are shown in U.S. Pat. Nos. 2,014,057 to Rogers; 2,447,300 to Williams; 2,797,832 to Weinmann; and 2,612,379 to Vogel. These clamps or clasps are generally pivotably mounted on and close to the main back frame of the hand truck, spring loaded, and may be adjusted vertically along the frame or a track to accommodate drums of differing heights. A similar type of clip structure is also disclosed in U.S. Pat. No. 2,693,968 to Bateman, although its purpose is to retain the platform section of a coin operated baggage cart in its folded position.
Of particular interest are U.S. Pat. Nos. 1,490,361 to Brown and 2,710,106 to Hanson. The Brown '361 and Hanson '106 patents each disclose hand trucks specially designed for use with drums or barrels, and have longer hooks for retaining a load against the rear frame.
In the Brown '351 patent, a "chime-hook" comprised of a flat bar with a curled, depending hook at each end is used to retain a load on the hand truck. The chime hook is slidably and rotatably mounted on a rod, the rod passing vertically through an aperture in the bar and through a hub or guide block which allows the height of the chime bar to be adjusted along the rod. The bar may then be pivoted over the rear edge of the drum, and lowered to engage the rim thereof.
In the Hanson '106 patent, the hook is longer and formed from a straight rod bent at one end to form a hook, and is normally stowed in an inoperable position with the hook end inserted through a hole in the angle irons of the frame. For use, the rod is removed from its stowed position and inserted through one of several central slots in the angle irons, with cross pins extending perpendicularly from the mid-portion of the rod being aligned axially with the slots. When the hook is in position, the rod is rotated so that hook end depends downwardly and catches the front edge of the load, and the cross pins depend downwardly and perpendicular to the slots so as to be engaged between the angle irons, thereby retaining the rod from forward or backward movement.
These hand truck designs, however, have failed to solve several of the problems or drawbacks with attempting to use a hand truck with a load such as a file cabinet. File cabinets are often placed in close contact side-by-side and against side or back walls, making them difficult to jockey, and even shorter file cabinets may contain extremely heavy loads of papers and files. Because file cabinets are often transferred without removing the contents, it is desirable to have a method of securing the file cabinet to the hand truck while it is in place between other file cabinets or a wall, lifting that file cabinet from this restricted position, and transporting the file cabinet without resecuring the file cabinet to the hand truck or placing additional padding to protect the front of the file cabinet.